Electric motor control apparatus



Patented Oct. 26, 1948 UNITED STATES: PATENT OFFICE ELECTRIC MOTOR CONTROL APPARATUS David L. Markusen, Minneapolis, Minn., assignmto Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application February 8, 1943, Seriai No. 475,113

5 Claims. l

The present invention relates to control apparatus, and particularly to apparatus for automatically operating the ilight control surfaces of an aircraft.

An object of the present invention is to pron vide an improved ilight control system for aircraft of the type shown and described in the copending application oi Willis I-I. Gille, Serial No. 447,989, tiled June 22, 1942. The system shown in the Gille application includes a system for controlling each ight control surface which is responsive to the resultant of two controlling conditions. In the case of the rudder, one of the controlling conditions is the deflection of the aircraft-from a predetermined course, as measured by a directional gyroscope, and the other controlling condition is the tilting oi the aircraft about a longitudinal axis passing through it from nose to tail, as measured by a vertical gyroscope. In the case of the ailerons, the same two controlling conditions are utilized. In the case of the elevator, the two controlling conditions are the attitude of the aircraft, or in other words its angular position with respect to an axis passing through it laterally from side to side, and the tilting of the aircraft about the longitudinal axis previously referred to. Both of these conditions are measured by a single vertical gyroscope.

In the system disclosed in the Gille application, the directional gyroscope is required to move two control potentiometers, one for producing a controlling effect on a rudder driving motor and the other for producing a controlling eect on an aileron driving motor. Likewise, one oi the axes of the vertical gyroscope in the Gille system is required to move three potentiometers, one potentiometer for each of the three motor control systems for the rudder, ailerons, and elevator. The operation of these potentiometers exerts a frictional torque on the gyroscope, which tends to upset their balance. It is desirable that the frictional load on the gyroscope be reduced as much as possible. In accordance with the principles described herein, I propose to reduce the fric tional load on a gyroscope used in a control system of the type shown by Gille, by utilizing a single potentiometer unit for introducing a control eiect into both the rudder and aileron control systems.

Itis therefor an object of the present invention to provide an improved system for controlling the night control surfaces of an aircraft of the type shown in the co-pending Gille application previously referred to.

A further object of this invention is to provide an improved electrical control system, wherein a plurality of variable conditions are used to simultaneously control a plurality of motors.

A further object is to provide, in a system of the type described, means whereby the operation of a single variable impedance may be utilized to introduce a control effect into each of a plurality of control systems. A still further object is to provide, in a, system of the type described, a motor control system utilizing an electronic amplier provided with an input transformer having a plurality of primary windings, and means responsive to a plurality of controlling conditions to individually vary the energization of the primary windings.

Other objects and advantages of the present invention will become apparent from a consideration cf the accompanying specification, claims and drawing, in which the single figure represents, somewhat diagrammatically, an electrical system for operating the flight control surfaces of an aircraft, embodying the principles of my invention.

Referring to the drawing, there is shown a rudder control system including a pulley I0 over which passes a cable Il which maybe attached to the rudder (not shown). The pulley I0 is driven by a. motor l2. The supply of electrical energy to the motor l2 is controlled by an amplifier I3 having a pair of input terminals I4 and l5 and power supply terminals 5 and i5. Power is supplied to the amplifier by a transformer l having a. primary winding 8 connected to any suitable source of power (not shown) and a secondary winding 9 connected to terminals 5 and 6. Electrical control signals impressed on the input terminals of amplifier I3 are produced by a rudder control network 24, which includes an input transformer i6, having a secondary winding l1 and a pair of primary winding 20 and 2l. The amplier I3 may be of any suitable type capable of energizing motor I2 for rotation in opposite directions depending upon the phase of the signal voltage. Such a motor and amplier are Well known in the art and need not be described speciically herein. Typical motor 'and amplifier combinations of the type which may be employed are those shown in the patent to Anschutz- Kaempfe 1,586,233 and the patent to Whitman 1,952,587. A motor and amplier combination which is particularly suitable for use in connection with the apparatus is one of the type described in the Gille application previously referred to, or the improved form disclosed and claimedin the joint application of Willis H. Gille, William tentiometer 26, and an adjustment network gen-` erally indicated at 21.

The rudder control potentiometer includes a slider which is movable along a slide-wire resistance 3| by a directional gyroscope schematically indicated at' 32. As long as the aircraft maintains a previously established course, the gyroscope 32 keeps the slider 30 in the center of resistance 3l. If the aircraft deviates from its course, the gyroscope 32 moves the slider 30 to the left or right along resistance 3| in accordance with such deviation.

The follow-up potentiometer 26 includes a slider 33 which is movable along a slide-wire resistance 34. The slider 33 is fastened to the same shaft as the pulley I0. The terminals of primary winding 20 are connected to sliders 33 and 30 by'conductors 22 and 23, respectively. A protective resistance 29 is connected in conductor 22, so that the primary winding 20 cannot be shunted by movement of both sliders 30 and 33 to the same ends of their respective slide-wires. If either of the primary windings should be substantially shunted, the impedance of the other primary winding would be lowered so that any signal impressed thereon would be considerably reduced in amplitude.

The terminals of resistance v3| are connected to the terminals 35 and 36 of the adjustment network input terminals 54 and 55. Input terminals Ell and 55 are connected to the secondary winding 55 of an input transformer E1 having primary windings 58 and 5o. The transformer 51 is a part of an aileron control network 33, which also includes an aileron control potentiometer 54, a follow-up potentiometer 65, and an adjustment network 5B. The primary winding 58 is connected by means of conductors 6I and B2 to the sliders of the potentiometers 64 and 55, respectively. A protective resistance 59 is connected in conductor 6|, for the same purpose as resistance 29 in the rudder con- 21. The terminals of resistance 34 are connected K to terminals31 and 33 of adjustment network 21. In the adjustment network 21 isthe secondary winding 28, which supplies electrical energy to the rudder control network.' 'I'he secondary winding is shown as a further winding of the transformer 1. The rudder control network 24 includes a form of Wheatstone bridge circuit. The construction and operation of this type of network is disclosed in detail in the Gille application previously mentioned, and will be described only briefly here.

The adjustment network 21 includes, in addition to the secondary winding 28, a centering adjustment 4|. The centering adjustment includes two rheostats 42 and 43 connected in adjacent arms of the bridge circuit= and simultaneously operable in opposite senses by means of a manual controller 44. A pointer associated with the controller 44 moves over a calibrated scale adjacent the controller to indicate the setting of the centering adjustment. By operation of this controller, the position of the rudder for any given position of the control potentiometer 25 may be adjusted.

A variable resistance 45 is' connected in parallel with resistance 3|, and xed resistances 46 and 41 are connected in the adjacent arms of the bridge circuit. As described in the Gille application, the variable resistance 45 operates as a ratio adjust-` ment. In other-words, its setting determines the distance through which the follow-up slider 33 must move in order to rebalance the bridge circuit after a given unbalancing movement of the control slider 30. V

There is also shown in the drawing an aileron control system in which a pulley 50 drives a cable 5|, which may be attached to the ailerons of the aircraft (not shown). The pulley 50 is driven by a motor 52 controlled by an amplifier 53 having trol system.

The adjustment network 65 is generally similar to the adjustment network 21 of the rudder control system. In order to facilitate an understanding of this adjustment network, the elements thereof have been given reference characters corresponding to the reference characters applied to the same elements in the adjustment network 21 but with the suffix A indicating that they are employed in connection with the aileron control system. Thus, the network is energized by the secondary winding 28A of a transformer 1A. The transformer 1A like transformer l has a secondary 9A connected to the power supply terminals 5A and 6A of amplifier 53. Interposed between the treminals of secondary 28A and the potentiometer 64 are two fixed resistors 46A and 41A. Interposed between the secondary 28A and the followup potentiometer 65 is a centering adjustment 4 I A and a ratio adjustment A. The centering adjustment 4|A, as is the case with the centering adjustment 4|, comprises two rheostats 42A and l QSA simultaneously operable in opposite senses by This centering means of a manual controller. adjustment enables the position of the ailerons for any given position of the control potentiometer 64 to be adjusted. The ratio controller 45A is in the form of a variable resistance in parallel with the follow-up potentiometer 65. This varies the distance through which the vfollow-up slider 65 -must move in order to rebalancethe bridge circuit after a given unbalancing movement of the control potentiometer 64.

It will be noted from the above that the only substantial difference bteween the adjustment network 66 and the adjustment network 21 is that in the case of the one just described the centering and ratio adjustmentsare located on the followup potentiometer side-of the secondary winding rather than on the control potentiometer side. It has been found desirable to employ the particular arrangement of the adjustment network in connection with the rudder control system because of the characteristic of the rudders of certain planes. Obviously, aside from the particular operating range desired, the arrangement of either adjustment network 21- or 66 can be employed.

The aileron control system 63 is generally similar electrically to the rudder control system Vas will be apparent from the foregoing description, and it is believed that a. further description thereof is unnecessary.

The aileron control potentiometer 64 is operated -by a vertical gyroscope 61, in accordance with the tilting of the aircraft about an axis paising through it longitudinally from nose to ta The resistance 3! in the rudder control network is provided with a center tap 10. A conductor 1| connects the center tap 10 with one terminal4 of the primary winding 60 on the input transformer 51 in the aileron control system. The other terminal of primary winding 50 is connected by means of a conductor 12 to the slider 30 of the rudder control potentiometer 25. A protective resistance 69 is connected in conductor 12 to prevent shunting 60 when slider 3| is at its center position.

The aileron control potentiometer 84 is provided With a center tap 13, which is connected through a conductor 14 to the lower terminal of primary winding 2| of input transformer I 6 in the rudder control system. The upper terminal of primary winding 2| is connected through a conductor 'i5 to the slider of the aileron control potentiometer 64. A protective resistance 19 is connected in conductor l5 to prevent shunting of winding 2|.

There is also shown in the drawing an elevator control system including a pulley 80 over which passes a cable 8| connected to the elevator surfaces (not shown). The pulley 80 is driven by a motor 82 controlled by an amplifier 83. The amplier 83 is provided with a signal potential which is the resultant of two signal potentials produced in a compensating network 84 and a main elevator control network 85. The main elevator control network includes an adjustment network 90 corresponding to the adjustment network 66 of the aileron control system. Since the elements and their arrangement in the network is identical to that of the aileron control system, the various elements have been given the same reference characters with the exception that the suihx E has been employed instead of the suii'ix A, the suiiix E indicating that the elements are concerned with the elevator control system. in view of the fact that the elements are identical, it is believed unnecessary in view of the similarity of the reference characters applied thereto to spe cically refer to these elements herein. The signal potential provided by the main network 85 is determined by the relative positions of an elevator control potentiometer 81 operated by the vertical gyroscope in accordance with the angular position of the aircraft with respect to its lateral axis and an elevator follow-up potentiometer 8B which is operated concurrently with the pulley 80.

The compensating network 84 is energized by a secondary Winding 9i constituting a further secondary Winding of a transformer '1E which supplies power to the amplifier 83 and to the main network 85. Also associated with the compensating net-Work is a control potentiometer 85 operated by the vertical gyroscope in accordance with the tilting of the aircraft about its longitudinal axis. prises a resistance element 93 and a slider 94 which is operatively connected to the gyro. The two terminals of the resistance 93 are connected together and to the right hand terminal of secondary 9| by conductors 95, 96, and 91. The left hand terminal of transformer 9| is connected by conductors 98 and 99 to the center tap of the potentiometer resistance 93. A rheostat comprising a resistance lili and slider |02 is connected by conductors 403, |04, and 99 between the center tap of resistor 93 and the slider 94. The slider |02 of this rheostat is connected by a conductor |05 to the left hand input terminal |07 of amplier 83. The other input terminal |08 of amplier 83 is connected by conductor |09 to the slider of the follow-up potentiometer 88.

Referring to the compensating network 84, it is to be noted that the secondary 9| is effectively connected between the center tap of resistor 93 and the two ends thereof. Furthermore, the resistance lili of the rheostat consisting of resistor This control potentiometer 8B comasuman wl and snoer m is connected Between the eentertap of resistor u and the slider ll. Thus upon any deviation of slider 9,4 from the midpoint of resistor 93 by reason of a tilting of the aircraft, a potential is impressed across resistor I 0|. Since the two terminals of the resistor 93 are connected together, the phase of this poten-l When the various control and follow-up poten-V tiometers are in the positions shown in the drawing, the aircraft is maintaining a straight course and the rudder and ailerons are in their normal positions. Under these conditions, let it be assuxned that the aircraft deviates from its course,

' and that the directional gyroscope 32 responds to this deviation by moving the slider 3U to the right along resistance 3|.

This motion of slider 30 unbalances the rudder control nework 24, and the unbalance potential existing between sliders 30 and 33 is transmitted through conductors 22 and 23, primary winding 20, and secondary windingA |1 to amplifier I3. This signal impressed on amplifier i3 causes the motor |2 to operate in a direction to deect the rudder so as to restore the aircraft to its previous course. At the same time, the slider 33 is moved to the right along resistance 3l to rebalance the control network 24.

Operation of slider 30 to the right along resistance 3i also produces a potential across primary winding 60 of input transformer 5l in the aileron control system. This potential is that existing between the slider 3B and the centerl tap 'l0 on resistance 3|. This potential is transmitted through primary winding 60 and secondary wind'- ing 5S of transformer 5 1 causing the amplifier 53 to energize motor 52 so as to drive the ailerons to a position such that the aircraft makes a properly banked turn in returning to its previous course.

As the aircraft tilts about its longitudinal axis in response to the operation of the ailerons, the vertical gyroscope 81 moves the slider oi' control potentiometer EL If the transformer windings supplying the rudder and aileron control networks are in phase with each other, so that the right hand terminal of resistance 3i of the rudder control potentiometer 25 is positive at the same time that the right hand terminal of the resistance in the aileron control potentiometer 64 is positive, then the slider of the aileron control potentiometer is moved at this time to the right along its associated resistance.

This movement of the control potentiometer 54 introduces an unbalancing eifect into the aileron control network 83 which causes a response of the motor 52 to drive the ailerons back toward their center position. At the same time, the move ment of the aileron control potentiometer 64 introduces, through the primary winding 2 I, a signal into the amplifier I3 of the rudder control system. This signal causes a response of the 7 motor I2 to restore the rudder torward its normal position.

As described in the Gille application, these restoring movements of the rudder and ailerons are made because it has been found that a smaller deflection of the rudder and ailerons is necessary to maintain an aircraft in a properly banked turn than ls required to bank and turn the aircraft from a straight level course.

From the foregoing discussion, it should be apparent that the -rudder control potentiometer produces a control eect on both the rudder and ailerons, and that the aileron control potentiometer 6I likewise produces a control effect on both the rudder and ailerons;

'Referring again to the condition which takes place when the plane is banked in connection vwith a turn, the vertical gyro is effective not only to move the potentiometer 64 but also to move the potentiometer 86. The result of this is that a voltage occurs between slider |02 andthe slider of potentiometer 81, this voltage'being dependent upon the amount of movement of the arm 94 of potentiometer 86 and the adjustment of slider I 02. The bridge is so designed that this voltage is of a phase to cause the elevator control system to be unbalanced in such a direction as to raise the elevators to cause upward movement of the plane. In other words. upon the banking occurring, a signal is introduced into the system such as to cause the plane to tend to rise slightly. The reason for this, as explained in the aforementioned Gille application, is to compensate for the upon the plane being placed into a bank during a turn is that which occurs whenever the plane is tilted for any reason. Thus, upon the plane being tilted, the ailerons and elevators are both deflected to cause the plane to be tilted back toits normal position and to temporarily cause the elevators to exert a climbing tendency on the plane to counteract the tendency to lose altitude due to the banking condition.

In the event of a plane tilting about atransverse axis, the potentiometer 81 is deflected in one way or the other. If the plane tilts downwardly, the signal introduced into amplifier 83 is of such phase as to cause the elevators to be raised to tend to cause the plane to climb. As the plane tends to level off, the elevators will-be returned to their normal position.

While I have shown and described a preferred embodiment of my invention, other modifications will occur to those skilled in the art and I therefore wish my invention to Abe limited only by the appended claims.

I claim as my invention:

1. Electrical control apparatus, comprising in combination, a plurality of load devices to be positioned, electrical motor means for driving each of said load devices, a balanceable electrical network including a control impedance and a rebalancing impedance, means for varying said control impedance to unbalance said network,v

means responsive to unbalance of said network for controlling one of said motor means, means driven by said one motor means for varying said 2. Electrical control apparatus, comprising in l combination, a pair of load devices to be positioned, electrical motor means for driving each of said load devices, and control means for said motor means comprising, for each motor means,

'a balanceable electrical network including a control impedance and a rebalancing impedance, means responsive to one of a pair of conditions indicativeV of the need for operation of said load devices for varying said control impedance to unbalance said network, an electronic amplifier for controlling said motor means, an input transformer for said amplier having a pair of primary windings, means connecting one of said windings to said network for energization in accordance with the unbalance of said network, means connecting the second of said windings to the control impedance in the other of said networks for energization in accordance with the other of said conditions, and means associated with each motor means and driven by said motor means for varying the rebalancing impedance of e the network associated with-said motor means.

3. An electrical control apparatus which includes: a rst 'motor means connected to and adapted to position a first load means; a second motor means connected to and adapted to position a second load means; a rst rebalanceable electrical network having a main control impedance therein; a second rebalanceable electrical network having a vmain control impedance therein; a first control means connected to said first motor means and adapted to control the operation thereof; a second control means connectedto said second motor means and adapted to control the operation thereof; a first transformer having a secondary winding connected to said rst control means, and a pair of primary windings; a second transformer having a secondary winding connected to said second control means, and a pair of primary windings; means connecting said first network to one primary of said first transformer, and connecting said main control impedance of said second network to the other primary of said first transformer; and means connecting said second network to one primary of said second transformer, and connecting said main control impedance of saidV rst network to the other primary of said second transformer.

4. An electrical control apparatus which includes: iirst and second load devices to be positioned; first and second motor means operable to position said first and second load devices, respectively: rst -and second electronic amplier means controlling the operation of said rst and second motor means respectively; a rst rebalanceable electrical network having a main control impedance, and a rebalancing impedance operated by said rst motor means; a second rebalanceable electrical network having a main control impedance, and a rebalancing impedance operated by said second motor means; a rst transformer having a secondary connected to the' input terminals of said first electronic amplifier to rebalance said net-- for controlling the operation thereof, and having a first primary winding connected to the entirety of said first network, and a second primary winding connected to said main control impedance of said second network; and a second transformer having a secondary connected to the input terminais of said second electronic amplifier for controlling the operation thereof, and having a rst primary Winding connected to the entirety of said second network, and a second primary winding connected to said main control impedance of said first network.

5. An electrical control apparatus which includes first and second motors to -be operated; first and second control means connected to said first and second motors respectively, for operation thereof a plurality of adjustable control networks each having a plurality of pairs of output connections the polarity across each pair of connectionsin any half cycle depending on the adjustment of said networks; a first transformer having a secondary winding connected to said first control means. a first primary winding con- -fnected across a pair of output connections of one network, and a second primary winding connected across a pair of output connections oi' a 

